The present invention relates to an electric tool with an electric motor adapted to drive a tool.
An electric tool of that kind has been known, for example, from U.S. Pat. No. 5,038,481. The known electric tool is a compass saw provided with a light source for observation of the cutting area. The light source may be connected via an optical waveguide.
Further, German patent application DE 197 14 248 A1 discloses a low-power motor unit for an electric tool which is particularly well-suited for dental applications, as drive for tooth drills, polishing, grinding, milling tools, screwing tools, or the like. In order to guarantee especially good handling properties, a supply unit for the low-power motor is connected with the low-power motor in rotating contactless fashion, for which purpose a plug-in connection and rotation-limiting means are preferably provided. The plug-in connection can be adapted to provide the connection of both the electric system and the fluid lines. Further, a lamp adapted to be coupled with the low-power motor via an optical waveguide can be provided in the working area of the electric tool.
More recently, there have been proposed by applicant electric tools that are controlled by means of optical switches each of which comprises two optical waveguides between which the transmission of light signals can be influenced via a control element. Depending on the signal received, the switch output is then controlled by an electronic evaluation unit.
Optical switches of that kind are known from U.S. patent application Ser. No. 10/214,844 which is fully incorporated by reference herewith.
In cases where optical waveguides are used in implementing optical switches or sensors of electric tools, this is done with the predominant aim to achieve high reliability as well as simple and low-cost assembly.